Reverting a WIP
You can revert a WIP that has already been merged (regardless of whether it was your or your teammate's):
hf revert xx-123
This will create a new WIP in your workspace that contains the “inverse” changes of XX-123.
After it's merged, all changes of XX-123 will be undone.
After issuing the revert command, you can look around, make sure everything is right, and then “merge” the WIP.